Conventionally, in this type of the hybrid system, also known is a hybrid system further including a so-called automatic control manual transmission between an output side of an automatic clutch and driving wheel sides. An input shaft of the manual transmission is coupled with a rotary element of a differential device on the same side as an output side of the automatic clutch. The hybrid system can start a vehicle by transmitting output torque of an engine to driving wheels via the differential device and a gear group so that a reaction force of output torque of the engine is caused to be in charge of a motor at the time of the vehicle start. Further, the hybrid system transmits the output torque of the engine to the driving wheels via the differential device and the gear group by causing the motor to be in charge of a reaction force of the output torque of the engine in a gear shift process between gear shift stages in a transmission. For example, the hybrid system having the configuration is disclosed in Patent Literature 1 described below.
Note that Patent Literatures 2 and 3 described below disclose hybrid systems each having an engine, a motor, an automatic control manual transmission interposed between the engine and driving wheels, a gear group for transmitting input torque to the driving wheel sides, and a differential device provided with plural rotary elements to which a torque input side of the gear group, a rotating shaft of the motor, an output shaft side of the engine, and an input shaft side of a transmission are individually connected, respectively. The hybrid systems carry out a smooth gear shift control with good responsiveness without depending on a friction control of an automatic clutch by carrying out a torque transition at the time of gear shift by the torque generated by the motor and a rotation number transition at an inertia phase by a rotation number control of the motor. Thus, the hybrid systems described in Patent Literatures 2 and 3 are not provided with the automatic clutch having one engagement member connected to an output shaft of the engine and the other engagement member connected to the rotary elements of the differential device. Further, Patent Literature 4 shown below discloses a technology for more increasing target torque of a motor that is power running driven when a charge state of a rechargeable battery is higher in a parallel hybrid system.